fix(peer-files): stream large cloud downloads + surface real errors (#30, #38)

Large peer downloads (~178MB) failed with a generic 'Operation failed', and
the download path had three stacked problems:

- The FIPS reqwest client used a hard-coded 20s total timeout regardless of the
  caller's .timeout(), so a big transfer over the mesh aborted at 20s before
  the Tor fallback could help. Honor the per-request timeout (client_with_timeout).
- The peer-content proxy buffered the whole file into node memory via
  resp.bytes() before sending a byte, and capped the transfer at 60s. Stream
  the body through with hyper::Body::wrap_stream (constant memory) and raise the
  timeout to 900s; bump the nginx peer-content read timeout to match.
- Free downloads pulled the file as base64 over RPC, doubling it in node memory
  and the browser — fatal for large files. Download free files by streaming
  from /api/peer-content straight to disk, after a 1-byte Range probe that
  surfaces the real reason (peer offline on mesh and Tor) instead of a generic
  failure. Paid downloads now return the real error through the {error} channel
  the UI already displays.

Adds the reqwest 'stream' feature for bytes_stream().

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

core/Cargo.lock

@@ -80,7 +80,7 @@ checksum = "a23eb6b1614318a8071c9b2521f36b424b2c83db5eb3a0fead4a6c0809af6e61"
 
 [[package]]
 name = "archipelago"
-version = "1.7.97-alpha"
+version = "1.7.98-alpha"
 dependencies = [
  "anyhow",
  "archipelago-container",
@@ -2156,10 +2156,12 @@ dependencies = [
  "tokio",
  "tokio-rustls 0.24.1",
  "tokio-socks",
+ "tokio-util",
  "tower-service",
  "url",
  "wasm-bindgen",
  "wasm-bindgen-futures",
+ "wasm-streams",
  "web-sys",
  "webpki-roots 0.25.4",
  "winreg",
@@ -3304,6 +3306,19 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "wasm-streams"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "15053d8d85c7eccdbefef60f06769760a563c7f0a9d6902a13d35c7800b0ad65"
+dependencies = [
+ "futures-util",
+ "js-sys",
+ "wasm-bindgen",
+ "wasm-bindgen-futures",
+ "web-sys",
+]
+
 [[package]]
 name = "web-sys"
 version = "0.3.85"